This invention relates to a tachometer system for an engine and more particularly to a tachometer that can be utilized with engines which have associated with them a separate power source such as a battery or wherein the engine has no such associated separate electrical power source.
Basically, tachometers may be considered to fall into two general types. The first type of tachometer is employed in applications wherein there is a separate source of electrical power such as a battery. This source of electrical power is supplied to the tachometer. The tachometer receives pulsating signals from the engine indicative of speed either from the ignition system or from its generating system and these signals are converted into a display indicative of engine speed.
With types of engines that do not have separate electrical power sources, then the magneto generator not only provides the speed detection signal but also the power for operating the tachometer. However, this type of device can cause a problem with the other electrical circuits of the engine due to the fact that the pulsating output signals have a high voltage and hence can generate noise that can adversely effect other electrical systems.
It is, therefore, a principal object of this invention to provide an improved and simplified tachometer for engines that can be utilized with both engines having separate electrical power sources and those having no separate electrical power source.
It is a further object of this invention to provide an improved and simplified tachometer that is capable of use in a wide variety of types of installations and which will not introduce external noise into the system.